/Engine/Plugins/Runtime/MassEntity/Source/MassEntity/Public/MassEntityManager.h
A "similar" archetype is an archetype exactly the same as SourceArchetype except for one composition aspect like Fragments or "Tags"
[FMassArchetypeHandle](API\Plugins\MassEntity\FMassArchetypeHandle) InternalCreateSimilarArchetype ( const [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< FMassArchetypeData > & SourceArchetype, const [FMassTagBitSet](API\Plugins\MassEntity\FMassTagBitSet) & OverrideTags )